Crystal holder



June 11, 1935. w MOSER r AL 2,004,170

CRYSTAL HOLDER Filed Feb. 6. 1934 XNVENTORS WILHELM MOSER Y LEO POLDZENG7kg MW ATTORNEY Patented June 11, 1935 UNITED STATES PATENT OFFICECRYSTAL HOLDER Application February 6, 1934, Serial No. 710,036 InGermany February 6, 1933 4 Claims.

This invention relates to an arrangement for crystal oscillatorscomprising a thermostat.

It is known from the prior art of thermostats combined with crystalsthat the crystal and electrodes together with means for the productionof heat (heater winding) and means for the indication and regulation ofthe temperature (indicator winding, bimetal-strip type of switch, or thelike) may be confined in an exhaust space or vessel. But it has beenfound that the materials used for insulation are liable to give offgases with the result that the vacuum is impaired. Another fact is thatthe exchange of heat between the heater winding or the indicator windingand the electrodes is impeded.

In order to obviate these drawbacks, in crystal thermostats in vacuo thesource furnishing the heat and optionally also the means controlling thetemperature are disposed outside the vacuous space according to thisinvention. For instance, all auxiliary windings for heating andtemperature indication are accommodated in the interior of a metallicelectrode, the electrode being so fused together with the wall of theglass vessel enveloping the vacuum that no gas-evolving insulators willbe in contact with the vacuum.

Inasmuch as the space available for the electrodes is very limited, andsince direct action between the heater winding and the indicator windingtends to reduce the accuracy of indication, arrangements, according toanother object of the invention, may be also so chosen that the heat isapplied to the electrodes by remote heating. This could be accomplished,for instance, by irradiation from a thermal radiator or by means ofaction from a generator which sets up eddy-currents in the electrodes.

The control of the thermal source can be effected by alternateconnection and disconnection by the agency of the temperature indicator(such as a contact thermometer) embedded in the electrode, or else bythe aid of a balanced resistance used as a temperature indicator actionmay be brought upon a bridge arrangement in which instance regulation iscontinuous.

Two embodiments of the invention are shown by way of example in theattached drawing. Referring to Fig. 1, I is the crystal which isdisposed in the exhaust glass vessel 2 between electrodes 3 and 4without making contact therewith. The supporting is insured mostpreferably between points or tips 5 which engage the quartz crystalplate at three points about its median plane. The bottom electrode 4 ishollow and contains the heater winding 6 and a bimetal-strip switch 1 inthe circuit of the heating winding.

8 denote the terminals for the crystal electrodes.

The exemplified embodiment shown in Fig. 2 differs from the one beforedescribed by that the heating winding 6 is disposed outside theelectrodes. It is fed from an alternating current source 9 withinterposition of the bimetal switch I and it insures the heating of theelectrodes by means of eddy-current heating.

We claim:

1. A piezo electric crystal holder comprising an oscillation crystaldisposed in a vacuum chamber, an upper and lower electrode for saidcrystal and located within said chamber, at least one of said electrodeshaving an aperture, a heater winding within said aperture, and abimetallic strip within said aperture, said bimetallic strip havingcontacts for controlling a current supply circuit for said heaterwinding.

2. A piezo electric crystal holder comprising an oscillation crystaldisposed in a vacuum chamber, an upper and lower electrode for saidcrystal and located within said chamber, at least one of said electrodeshaving an aperture, a bimetallic strip within said aperture, and aheater winding surrounding the outside of said chamber, said bimetallicstrip having contacts for controlling the current supply for said heaterwinding.

3. A piezo electric crystal holder comprising an oscillation crystaldisposed in a vacuum chamber, an upper and lower electrode for saidcrystal and located within said chamber, at least one of said electrodeshaving an aperture, a bimetallic strip within said aperture, and aheater winding located outside of said chamber at a position whichsurrounds said electrode so as to insure the heating of said electrodeby means of eddycurrent heating, said bimetallic strip having contactsfor controlling the current supply circuit for said heater winding.

4. A piezo electric crystal holder comprising an oscillation crystaldisposed in a vacuum chamber, an upper electrode having a ring-likeportion surrounding said crystal, a lower electrode having a ring-likeportion surrounding said crystal, said lower electrode having anaperture which is brought outside of said chamber, a bimetallic stripwithin said aperture, and a heater winding located outside of saidchamber at a position which surrounds said electrode so as to insure theheating of said electrode by means of eddy-current heating, saidbimetallic strip having contacts for controlling the current supplycircuit for said heater winding.

WILHELM MOSER. LEOPOLD LENG.

